Effect of saliva substitutes in combination with fluorides on remineralization of subsurface dentin lesions

Prevention of Root Caries Using Oxalic Acid

Certain dentin hypersensitivity treatment materials include oxalic acid to coat dentin surfaces with minerals, while certain organic acids possess a remineralization effect. Herein, an organic acid that inhibits the demineralization and coating of root surfaces was evaluated. Specimens were produced using five non-carious extracted bovines. Four different acids were used: oxalic acid (OA), malonic acid (MA), polyacrylic acid (PA), and succinic acid (SA). Each acid was applied to the root surface and washed using distilled water or a remineralization solution, and the surface was observed using scanning electron microscopy (SEM). All the surfaces of each specimen, barring the polished surface, were covered with wax and immersed in an automatic pH cycling system for two weeks. Dentin demineralization was analyzed using transverse microradiography (TMR) before and after pH cycling. SEM analysis demonstrated that the three acid groups demineralized the dentin surface, whereas the OA group generated crystals covering the dentin surface, even in a distilled water environment. TMR analysis revealed that the OA groups showed significantly lower integrated mineral loss compared with the other groups, even in the distilled water environment. The results suggest that OA generates insoluble calcium oxalate crystals on the dentin and suppresses demineralization even under low saliva conditions.

Application of Amorphous Calcium Phosphate Agents in the Prevention and Treatment of Enamel Demineralization

Enamel demineralization, as a type of frequently-occurring dental problem that affects both the health and aesthetics of patients, is a concern for both dental professionals and patients. The main chemical composition of the enamel, hydroxyapatite, is easy to be dissolved under acid attack, resulting in the occurrence of enamel demineralization. Among agents for the preventing or treatment of enamel demineralization, amorphous calcium phosphate (ACP) has gradually become a focus of research. Based on the nonclassical crystallization theory, ACP can induce the formation of enamel-like hydroxyapatite and thereby achieve enamel remineralization. However, ACP has poor stability and tends to turn into hydroxyapatite in an aqueous solution resulting in the loss of remineralization ability. Therefore, ACP needs to be stabilized in an amorphous state before application. Herein, ACP stabilizers, including amelogenin and its analogs, casein phosphopeptides, polymers like chitosan derivatives, carboxymethylated PAMAM and polyelectrolytes, together with their mechanisms for stabilizing ACP are briefly reviewed. Scientific evidence supporting the remineralization ability of these ACP agents are introduced. Limitations of existing research and further prospects of ACP agents for clinical translation are also discussed.

Erosive assessment of dry mouth lozenges and tablets on enamel and dentin

OBJECTIVES

To assess the erosive potential of dry mouth lozenges and tablets on enamel and dentin.

MATERIALS AND METHODS

The following lozenges and tablets were tested: Salese, Oracoat Xylimelts, Cotton Mouth, TheraBreath, DenTek OraMoist, SmartMouth, ACT, CVS Health, Rite Aid, Med Active, and Hager Pharma. pH Analysis: Each lozenge or tablet was crushed with a pestle and mortar and 5 g of the resultant powder was dissolved in 10 ml of distilled water (pH 7.02) The pH of each lozenge solution was assessed by using a calibrated pH meter. Titratable Acidity (TA) was determined by adding 0.1 M of NaOH to each homogenous tablet solution until the pH reached 7.0. Gravimetric Analysis was measured with freshly extracted molars crown/roots were sectioned at the CEJ and enamel and dentin specimens were fabricated. The specimens were then submerged in 5 ml of solution containing 2.5 gm of crushed tablets for 24 h, 48 h, 96 h and 14 days with measurements performed at each interval after drying. The solutions were renewed at each interval.

RESULTS

Significant correlation between pH and TA was observed for lozenges and tablets evaluated (p < 0.0001). Both variables were strongly correlated with enamel and dentin loss (p < 0.0001). For enamel, DenTek resulted in significantly more substance loss (p < 0.05) than with the other tested products, while Xylimelts presented the lowest percentage of substance loss. For dentin, Cotton Mouth resulted in the highest substance loss, and Xylimelts presented the lowest percentage of substance loss.

CONCLUSIONS

There is a strong correlation between the pH, tritatable aciditiy, and erosive potential of these products. DenTek and Cotton Mouth reported erosive effect to the enamel and dentin, respectively. Xylimelts performed better than the rest of the products in relationship to enamel and dentin.

Comparison of Fluoride Ion Release from Fluoride Gel in Various Solvents

OBJECTIVE

The aim of this study was to determine the concentration of fluoride ions present in various solvent solutions and compare it to the label amount of fluoride concentration.

MATERIAL AND METHODS

The gel containing amine fluoride and sodium fluoride was compared to gel containing sodium fluoride only. The solvents used in this study were distilled water, redistilled water, tap water, 0.9% sodium chloride solution and the artificial saliva. The amount of fluoride ion (F^-) was determined by the use of fluoride ion-selective electrode. The ANOVA and the Post hoc Tukey's test were used. The significance level was α = 5%.

RESULTS

The differences between F^- ion release in various solvents were statistically significant (p < 0.05). The F^- ion concentrations measured in both gels' redistilled water solutions were higher than the label concentration. There was a significant difference in fluoride ion release in sodium fluoride only gel solutions. Fluoride ion release was significantly different in combined fluoride gel solutions.

CONCLUSIONS

Amine fluorides do not interact with other ions present in the solution, whereas F^- ion release from sodium fluoride alters when other ions are dissolved in the same solution. Amine fluorides deliver F^- ions for caries prevention more efficiently.

Patient-related outcomes in Sjögren syndrome treated with stimulants of salivary secretion: Randomized clinical trial

OBJECTIVES

To investigate the impact of gustatory stimulants of salivary secretion (GSSS) on Sjögren's syndrome patients' self-perception of xerostomia, oral health-related quality of life (OHRQoL) and salivary secretion.

METHODS

A total of 110 Sjögren's syndrome patients were randomly allocated to be treated with either a malic acid lozenge or a citric acid mouthwash and then crossed over. Before and after the interventions, the Xerostomia Inventory 5 (SXI-5-PL) and the Oral Health Impact Profile (OHIP-14-PT) questionnaires (both in the Portuguese language) were administered to patients. Unstimulated, mechanical and gustatory-stimulated salivary flows were determined. Repeated measures and between-subject analyses were performed. Statistical significance was set at 5%.

RESULTS

After the intervention and within each group, both GSSS elicited a reduction in the SXI-5-PL and OHIP-14-PT scores and an increase in salivary output, significant in the malic acid lozenge group. The malic acid treatment resulted in a greater effect size and percentage improvement than citric acid mouthwash. The malic acid lozenge also produced a significant greater salivary output than the citric acid rising solution.

CONCLUSIONS

In Sjögren's syndrome patients, lozenges containing malic acid increased saliva production and xerostomia relief, resulting in improved quality of life.

Effect of NaF, AmF, KF gels and NaF toothpaste combined with a saliva substitute on dentin lesions in vitro

OBJECTIVE

The aim of the present in vitro study was to evaluate the remineralizing effects of NaF, AmF, KF gels and NaF toothpaste in combination with a potentially demineralizing saliva substitute (Glandosane; pH = 5.1) being widely used in Germany.

METHODS

In each of 120 dentin specimens, three artificial lesions were created. One lesion was covered for analysis of pre-demineralization (ΔZ_B). Treatments during pH cycling (3 × 1 h demineralization/day [pH = 5.0] and 3 × 3 h Glandosane/day; 12 h 100%humidity) were as follows: no treatment (NT), application (5 min,2×/day) of 12.500 ppm F^- [pH = 6.04] (NaF-gel₁), 12.500 ppm F^- [pH = 7.34] (NaF-gel₂), 12.500 ppm F^- [pH = 5.82] (AmF-gel), 1450 ppm F^- [pH = 7.35] (KF-gel), and 5000 ppm F^- [pH = 8.14]; (NaF-TP) for 7 days (E1). Subsequently, from each specimen, one lesion was covered, while the remaining lesion was cycled for another 7 days (E2). Differences in integrated mineral loss (ΔΔZ_E1/ΔΔZ_E2) were calculated between values before and after pH cycling.

RESULTS

Mean (95%CI) ΔZ_B was 3851 (3762;3939) vol% × μm. Except for NaF-gel₂ and NaF-TP, specimens of all other groups further demineralized. Only NaF-gel₂ induced a significant gain in mineral content (p ≤ 0.004; paired t test). Significant differences in the change of mineral loss were found between NT and all fluoride groups for both ΔΔZ_E1 and for ΔΔZ_E2 (p < 0.05, Bonferroni post hoc test). However, only NaF-gel₂ and NaF-TP induced remineralization.

CONCLUSION

Under the in vitro conditions chosen, all fluoride agents could significantly hamper the adverse effects of a demineralizing saliva substitute.

CLINICAL SIGNIFICANCE

In combination with a demineralizing saliva substitute, slight mineral gain was only observed for neutral NaF-gel₂ and 5000 ppm F^- toothpaste.

Toothpaste prevents debonded brackets on erosive enamel

This study evaluated the effect of high fluoride dentifrice on the bond strength of brackets after erosive challenge. Eighty-four enamel specimens were divided into seven groups (n = 12): WN (distilled water/no acid challenge), W3C (distilled water/3 cycles of acid challenge), and W6C (distilled water/6 cycles of acid challenge) were not submitted to dentifrice treatment. Groups RF3C (regular fluoride dentifrice/3 cycles of acid challenge) and RF6C (regular fluoride dentifrice/6 cycles of acid challenge) were treated with dentifrices containing 1450 μg F⁻/g and HF3C (high fluoride dentifrice/3 cycles of acid challenge) and HF6C (high fluoride dentifrice/6 cycles of acid challenge) were with 5000 μg F⁻/g. Acid challenges were performed for seven days. After bond strength test, there was no significant difference among groups submitted to 3 cycles of acid challenge (P > 0.05). Statistically significant difference was found between the regular and high fluoride dentifrices after 6 cycles of acid challenge (<0.05). Similar areas of adhesive remaining were found among control groups and among groups W6C, RF3C, RF6C, HF3C, and HF6C. The high fluoride dentifrice was able to prevent the reduction of bond strength values of brackets submitted to acid challenge. Clinical relevance: the high fluoride toothpaste prevents debonded brackets on erosive enamel.

Saliva substitutes in combination with high-fluoride gel on dentin remineralization

OBJECTIVE

This study aimed to determine whether the application of a high-fluoride gel could increase the remineralization of subsurface dentin lesions stored in saliva substitutes.

MATERIALS AND METHODS

Demineralized bovine dentin specimens were stored in mineral water (W), Glandosane (G), or modified Saliva natura (SN). Different treatments were applied twice daily: no treatment, Elmex sensitive mouth rinse (E), ProSchmelz gel (P), Duraphat toothpaste (D), ED, PD, and EPD. Differences in mineral loss were evaluated by transversal microradiography after 2 and 5 weeks.

RESULTS

The treatments with E, D, and ED inhibited the mineral loss induced by G and enabled some mineral gain. ProSchmelz was not able to inhibit the demineralizing effect of G. This high-fluoride gel induced an erosive mineral loss in combination with G. The use of ProSchmelz in combination or not with other fluoride products did not increase remineralization of specimens stored in SN or W (p > 0.05). ProSchmelz resulted in an erosion of the specimens stored in W and revealed a lower mineralized surface layer of specimens stored in SN.

CONCLUSION

Topical application of high-fluoride gel reduced the mineral loss induced by G but resulted in an erosion of specimens' surface. In addition, ProSchmelz did not demonstrate beneficial effects in combination with SN on subsurface dentin lesion remineralization.

CLINICAL RELEVANCE

Within the limitations of an in vitro study, it was concluded that the application of a high-fluoride gel did not promote additional effects on remineralization of subsurface dentin lesions in combination with saliva substitutes when compared to products with lower fluoride concentration.